ApostropheCMS Apostrophe up to 2.17.6 HTML Sanitizer index.js HTML injection

Summaryinfo

A vulnerability described as problematic has been identified in ApostropheCMS Apostrophe up to 2.17.6. Impacted is an unknown function of the file packages/sanitize-html/index.js of the component HTML Sanitizer. Executing a manipulation can lead to HTML injection. The identification of this vulnerability is CVE-2026-84371. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as problematic was found in ApostropheCMS Apostrophe up to 2.17.6. This vulnerability affects an unknown code block of the file packages/sanitize-html/index.js of the component HTML Sanitizer. The manipulation with an unknown input leads to a html injection vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. CVE summarizes:

ApostropheCMS is an open-source Node.js content management system, and sanitize-html provides a simple HTML sanitizer with a clear API. From version 1.9.0 until version 2.17.7, packages/sanitize-html/index.js validates an animation value attribute as one flat URL and does not recognize that attributeName selecting href or xlink:href gives the sibling values, from, to, or by attribute SVG SMIL URL semantics. In configurations that allow the animate, animateColor, animateMotion, animateTransform, or set elements, a values list can begin with a safe fragment and contain a later executable destination that survives allowedSchemesAppliedToAttributes checking. When the sanitized SVG is rendered, the browser can copy that later destination into the live link, and a victim who activates the link can execute script in the application's origin. This issue is fixed in version 2.17.7.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-84371 since 09/01/2026. The exploitation appears to be easy. The attack can be initiated remotely. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1059.007.

Upgrading to version 2.17.7 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-69654). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

• ApostropheCMS

Name

• Apostrophe

Version

• 2.17.0
• 2.17.1
• 2.17.2
• 2.17.3
• 2.17.4
• 2.17.5
• 2.17.6

Website

• Product: https://github.com/apostrophecms/apostrophe/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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